Method for smelting steel bar for sucker rod by ecological electric furnace

Abstract

The application discloses a method for smelting oil pumping rod steel bars by using an ecological electric furnace and belongs to the special steel field. The oil pumping rod steel bar is composed of the following components in percentage by mass: C: 0.39-0.43%, Si: 0.20-0.35%, Mn: 0.52-0.67%, P: ≤0.012%, S: ≤0.006%, Cr: 0.92-1.07%, Ni: ≤0.20%, Mo: 0.16-0.23%, V: 0.06-0.10%, Cu: ≤0.10%, and the balance of iron and inevitable impurities. The method comprises the following steps: ecological electric furnace, LF refining, RH refining, continuous casting, annealing, heating furnace heating, rolling and heat preservation. The ecological electric furnace continuous casting process batch production of the oil pumping rod steel bar is realized.

Description

Technical Field

[0001] This invention belongs to the field of special steel, specifically relating to a method for smelting steel bars for sucker rods using an eco-friendly electric furnace. Background Technology

[0002] As a core piece of equipment in oil extraction, the sucker rod is a crucial force-transmitting component connecting the surface pumping unit and the downhole pump, and its performance directly determines oil production efficiency and operational safety. Sucker rod steel bars, as the basic raw material for manufacturing sucker rods, have a profound impact on the stability of the oil extraction industry due to their quality and supply capacity. Therefore, the performance of sucker rod steel directly determines the reliability, durability, and dynamic performance of the sucker rod. Thus, developing a sucker rod steel bar with low cost, excellent mechanical properties, and high steel purity to meet the requirements of high-end products is essential. Summary of the Invention

[0003] The purpose of this invention is to provide a method for smelting sucker rod steel bars using an eco-electric furnace. This method employs an eco-electric furnace + LF refining + RH refining + continuous casting smelting process, along with a rolling process, to produce sucker rod steel bars. This method ensures both the mechanical properties and high purity of the finished steel bars, as well as the surface quality, meeting high-end application requirements and achieving a breakthrough in the mass production of sucker rod steel bars using an eco-electric furnace continuous casting process.

[0004] To achieve the above-mentioned objectives, this invention provides a method for smelting steel bars for sucker rods using an eco-friendly electric furnace, including composition design and process design. The specific steps are: eco-friendly electric furnace → LF refining → RH refining → continuous casting → heating → rolling. This method meets the quality requirements for steel bars for sucker rods, and the mechanical properties and high steel purity also meet the standard requirements.

[0005] A method for smelting steel bars for sucker rods using an eco-friendly electric furnace, wherein the chemical composition of the steel bars for sucker rods, by mass percentage, is: C: 0.39%–0.43%, Si: 0.20%–0.35%, Mn: 0.52%–0.67%, P: ≤0.012%, S: ≤0.006%, Cr: 0.92%–1.07%, Ni: ≤0.20%, Mo: 0.16%–0.23%, V: 0.06%–0.10%, Cu: ≤0.10%, with the balance being iron and unavoidable impurities.

[0006] The process route is as follows: Eco-friendly electric furnace → LF refining → RH refining → continuous casting → annealing → heating furnace heating → rolling → heat preservation; wherein...

[0007] The eco-friendly electric furnace smelting process is as follows: It employs a 100% scrap steel smelting process by mass fraction, comprising 70%–80% heavy scrap and 20%–30% light scrap; electrode heating time is 16–20 minutes; tapping temperature is 1540–1550℃; carbon content at tapping is 0.06–0.08%, phosphorus ≤ 0.010%; auxiliary materials and alloys are added when 1 / 4–1 / 3 of the steel has been tapped; the smelting cycle is 30–40 minutes; the oxygen content in the molten steel is 520–530 ppm; and the furnace oxygen consumption is 14–16 m³ / min. 3 / t steel. Alloy addition per ton of steel: silicon-manganese alloy 6.5~6.7kg / t, high-carbon ferrochrome 16.5~16.7kg / t, aluminum wire segments ( 10-16mm) 1.5~1.6kg / t. Auxiliary material addition per ton of steel: Steel ladle lime 5.8~5.9kg / t, active lime ( 10-70mm) 33~34kg / t, dolomite ( 20-70mm) 25~26kg / t, coke particles 13~14kg / t.

[0008] Furthermore, the LF furnace refining process is as follows: LF inlet temperature is 1520–1530℃, slag is formed by high current heating at 35000–36000A. When the slag surface fluctuates and the molten steel and electric arc are not exposed, 11–11.5 kg / t of active lime is added. After 10–15 minutes, the first sample is taken for chemical composition analysis. Alloy, silicon carbide, and alumina balls are added according to the target values ​​in the chemical composition, and coke particles are added to increase carbon content. The alloy, silicon carbide, alumina balls, and coke particles should be added to the argon flow to promote rapid melting and homogenization. When the molten steel temperature reaches 1580–1590℃, a deoxidizer (aluminum wire segment) is added. For steel with a thickness of 10-16mm, add 0.4-0.42 kg / t of steel to adjust the slag basicity. Close the furnace door for 15-17 minutes. When the steel temperature reaches 1600-1610℃, take a second sample to analyze the chemical composition to confirm the deviation of each chemical element content from the target value. After the second sample is taken, leave the furnace when the steel temperature reaches 1615-1620℃. The LF smelting cycle is 80-90 minutes, with a net clearance of 440-460 mm and a slag thickness of 130-150 mm. The following alloys are added per ton of steel: ferrosilicon 0.70-0.72 kg / t, high-carbon ferromanganese 1.70-1.75 kg / t, high-carbon ferrochrome 0.90-0.92 kg / t, ferromolybdenum 3.5-3.6 kg / t, and ferrovanadium (FeV50-B) 3.5-3.6 kg / t. Additional auxiliary materials added per ton of steel: 0.85-0.90 kg / t of coke particles, 2.0-2.1 kg / t of silicon carbide, and 1.5-1.6 kg / t of alumina balls.

[0009] Further, the RH refining process is as follows: inlet temperature 1620–1630℃, operation time 40–45 minutes; argon pressure controlled at 0.1–0.3 MPa before vacuum pump startup, ensuring the molten steel is not exposed by slight slag movement; timing begins when vacuum reaches 95–100 Pa, held for 15–20 minutes, while simultaneously adjusting argon pressure to 0.3–0.5 MPa; repressurization temperature 1580–1590℃; after static argon blowing, a covering agent (carbonized rice husk) of 0.6–0.65 kg / t steel is added; clearance 390–400 mm; outlet temperature 1570–1580℃. After vacuum breaking, silicon-calcium alloy cored wire is added (…). 14-15mm) 0.80~0.85kg / t steel.

[0010] Furthermore, the continuous casting process is as follows: ladle arrival temperature 1560~1570℃, tundish H controlled ≤1.8ppm, casting time 40min~50min, superheat 20~25℃, casting speed 0.44~0.45m / min; full-process protective casting, and the mold flux using medium carbon steel flux at 2.0~2.1kg / t steel.

[0011] Furthermore, the annealing process is as follows: the billet is annealed in an annealing furnace at a heating rate of 1.4 to 1.5°C / min, reaching 620 to 630°C, held for 5.6 to 6.0 hours, and then cooled in the furnace until the temperature is ≤90°C before being removed from the furnace.

[0012] Furthermore, the heating process is as follows: the furnace inlet temperature is 550℃~570℃; the preheating section temperature is required to be 780℃~800℃ for 1.3~1.4h; the second heating section temperature is required to be 900℃~910℃ for 1.9~2.0h; the first heating section temperature is required to be 1210℃~1220℃ for 1.3~1.5h; the soaking section temperature is required to be 1200℃~1210℃ for 1.2~1.3h; and the tapping temperature is 1190℃~1200℃.

[0013] Furthermore, the rolling process includes primary rolling and continuous rolling, specifically: Preliminary rolling: 11 passes, turning over → Pass 1: Width 408-408.1mm, Height 420-420.1mm, Reduction 65-65.1mm, Roll gap 260-260.1mm → Pass 2: Width 428-428.1mm, Height 355-355.1mm, Reduction 65-65.1mm, Roll gap 195-195.1mm → Turning over → Pass 3: Width 371-371.1mm, Height 348-348.1mm, Reduction 80 ~80.1mm, roll gap 188~188.1mm → 4th pass: width 394~394.1mm, height 273~273.1mm, reduction 75~75.1mm, roll gap 113~113.1mm → Turning steel → 5th pass: width 286~286.1mm, height 349~349.1mm, reduction 45~45.1mm, roll gap 189~189.1mm → 6th pass: width 300~300.1mm, height 304~304.0mm 1mm, reduction 45~45.1mm, roll gap 144~144.1mm → Turning steel → 7th pass: width 315~315.1mm, height 254~254.1mm, reduction 50~50.1mm, roll gap 94~94.1mm → 8th pass: width 330~330.1mm, height 204~204.1mm, reduction 50~50.1mm, roll gap 44~44.1mm → Turning steel → 9th pass: width 213~213.1mm, height 230~230.1mm, reduction 30~30.1mm, roll gap 140~140.1mm → 10th pass: width 252~252.1mm, height 270~270.1mm, reduction 30~30.1mm, roll gap 109~109.1mm → 11th pass: width 298~298.1mm, height 250~250.1mm, reduction 20~20.1mm, roll gap 88~88.1mm, then enters a 7-stand continuous rolling mill for rolling.

[0014] Continuous rolling process: 7 passes. Pass 1: Height 229–229.01 mm, width 245–245.01 mm, rolling speed 0.27–0.272 m / s; Pass 2: Height 192–192.01 mm, width 235–235.01 mm, rolling speed 0.31–0.312 m / s; Pass 3: Height 200–200.01 mm, width 195–195.01 mm, rolling speed 0.35–0.352 m / s; Pass 4: Height 166–166.01 mm, width 206–206 mm. The first pass has a height of 0.01 mm and a width of 176-176.01 mm, with a rolling speed of 0.435-0.437 m / s; the second pass has a height of 135-135.01 mm and a width of 180-180.01 mm, with a rolling speed of 0.510-0.512 m / s; the third pass has a height of 148.4-148.41 mm and a width of 148.4-148.41 mm, with a rolling speed of 0.613-0.615 m / s; the finished product is produced after the seventh pass.

[0015] Furthermore, the insulation is as follows: steel insulation, the temperature in the lower insulation pit is ≥550℃, the insulation time is 48~52h, and the temperature after exiting the pit is ≤100℃.

[0016] Furthermore, the insulated steel undergoes heat treatment, which includes the following steps: (1) Quenching: 840~860℃, hold for 1.0~1.2h, oil cooling; (2) Tempering: 550~570℃, heat preservation for 2.1~2.3h, water cooling.

[0017] The beneficial effects of this invention are: (1) Steel bars for sucker rods are produced using an ecological electric furnace + LF refining + RH refining + continuous casting smelting process and rolling process to meet mechanical performance requirements.

[0018] (2) Reasonable composition design and production process ensure surface quality and mechanical properties.

[0019] (3) The low magnification structure and non-metallic inclusions of the finished steel meet the requirements of high-end products. Detailed Implementation

[0020] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0021] Example 1 1. Chemical composition of steel bars for sucker rods The chemical composition by mass percentage is: C: 0.41%, Si: 0.26%, Mn: 0.58%, P: 0.010%, S: 0.005%, Cr: 0.98%, Ni: 0.04%, Mo: 0.19%, V: 0.08%, Cu: 0.05%, with the balance being iron and unavoidable impurities.

[0022] 2. Manufacturing process of steel bars for sucker rods Process route: Eco-friendly electric furnace + LF refining + RH refining + continuous casting → annealing → heating furnace heating → rolling → holding → heat treatment. Among them: 1) Eco-friendly electric furnace smelting The smelting process, based on mass fraction, employs 100% scrap steel, comprising 75% heavy scrap and 25% light scrap. The electrode heating time is 18 minutes, the tapping temperature is 1546℃, and the carbon content at tapping is 0.07% and phosphorus content is 0.008%. Auxiliary materials and alloys are added when 1 / 4 of the steel has been tapped. The smelting cycle is 35 minutes, the oxygen content in the molten steel is 525 ppm, and the furnace oxygen consumption is 15 m³ / min. 3 / t steel. Alloy addition per ton of steel: silicon-manganese alloy 6.6kg / t, high-carbon ferrochrome 16.6kg / t, aluminum wire segments ( 12mm) 1.5kg / t. Auxiliary material addition per ton of steel: Steel ladle ash 5.8kg / t, active lime ( 30mm) 34kg / t, dolomite ( 35mm) 26kg / t, coke granules 13kg / t.

[0023] 2) LF furnace refining The LF inlet temperature is 1525℃, and a high current of 35500A is used for heating and slag formation. When the slag surface fluctuates and the molten steel and electric arc are not exposed, 11.2 kg / t of active lime is added. After 12 minutes, the first sample is taken for chemical composition analysis. According to the target chemical composition values, alloy, silicon carbide, and alumina balls are added, along with coke particles for carbonization. The alloy, silicon carbide, alumina balls, and coke particles should be added to the argon flow to promote rapid melting and homogenization. When the molten steel temperature reaches 1585℃, deoxidizer aluminum segments are added. 0.41 kg / t of slag (12mm) was added to adjust the slag basicity. The furnace door was closed for 16 minutes. When the molten steel temperature reached 1605℃, a second sample was taken to analyze the chemical composition to confirm the deviation of each chemical element content from the target value. After the second sample was taken, the molten steel temperature reached 1617℃ and the furnace was removed from the station. The LF smelting cycle was 85 minutes, with a net clearance of 450 mm and a slag thickness of 140 mm. The following alloys were added per ton of steel: ferrosilicon 0.71 kg / t, high-carbon ferromanganese 1.72 kg / t, high-carbon ferrochrome 0.91 kg / t, ferromolybdenum 3.5 kg / t, and ferrovanadium (FeV50-B) 3.6 kg / t. The following auxiliary materials were added per ton of steel: coke particles 0.87 kg / t, silicon carbide 2.0 kg / t, and alumina balls 1.6 kg / t.

[0024] 3) RH refining The inlet temperature was 1625℃, and the operation time was 42 minutes. Before starting the vacuum pump, the argon pressure was controlled at 0.16 MPa to ensure the molten steel was not exposed due to slight movement of the slag surface. Timing began when the vacuum reached 97 Pa and was maintained for 18 minutes. Simultaneously, the argon pressure was adjusted to 0.35 MPa, and the re-pressure temperature was 1585℃. After static argon blowing, 0.62 kg / t of carbonized rice husk was added as a covering agent. The clearance was 395 mm, and the outlet temperature was 1575℃. After breaking the vacuum, silicon-calcium alloy cored wire was added. 14mm) 0.82kg / t.

[0025] 4) Continuous casting The ladle temperature upon arrival is 1565℃, the tundish H is controlled at 1.5ppm, the casting time is 45min, the superheat is 22℃, the casting speed is 0.44m / min, the entire casting process is protected, and 2.1kg / t of medium carbon steel protective slag is used in the crystallizer.

[0026] 5) Annealing of the cast billet The billet is annealed in an annealing furnace at a heating rate of 1.5℃ / min, reaching 625℃, and held for 5.7 hours. It is then cooled in the furnace and removed from the furnace at 70℃.

[0027] 6) Heating The initial temperature in the heating furnace is 560℃; the preheating section temperature is required to be 790℃ for 1.4 hours; the second heating section temperature is required to be 905℃ for 1.9 hours; the first heating section temperature is required to be 1216℃ for 1.4 hours; the soaking section temperature is required to be 1207℃ for 1.3 hours; and the tapping temperature is 1197℃.

[0028] 7) Rolling Preliminary rolling: 11 passes, turning over → Pass 1: Width 408mm, Height 420mm, Reduction 65mm, Roll gap 260mm → Pass 2: Width 428.1mm, Height 355.1mm, Reduction 65.1mm, Roll gap 195.1mm → Turning over → Pass 3: Width 371mm, Height 348mm, Reduction 80mm, Roll gap 188mm → Pass 4: Width 394mm, Height 273mm, Reduction 75mm, Roll gap 113.1mm → Turning over → Pass 5: Width 286.1mm, Height 349.1mm, Reduction 45mm, Roll gap 189.1mm → Pass 6: Width 300.1mm, Height 304.01mm, Reduction... 45.1mm, roll gap 144mm → Turn over → 7th pass: width 315mm, height 254mm, reduction 50mm, roll gap 94.1mm → 8th pass: width 330.1mm, height 204.1mm, reduction 50mm, roll gap 44.1mm → Turn over → 9th pass: width 213.1mm, height 230.1mm, reduction 30.1mm, roll gap 140mm → 10th pass: width 252.1mm, height 270.1mm, reduction 30.1mm, roll gap 109.1mm → 11th pass: width 298mm, height 250.1mm, reduction 20.1mm, roll gap 88.1mm, then enters a 7-stand continuous rolling mill for rolling.

[0029] Continuous rolling process: 7 passes. Pass 1: Height 229mm, width 245.01mm, rolling speed 0.272m / s; Pass 2: Height 192.01mm, width 235.01mm, rolling speed 0.312m / s; Pass 3: Height 200.01mm, width 195mm, rolling speed 0.352m / s; Pass 4: Height 166.01mm, width 2... The first pass has a height of 6.01 mm and a width of 176 mm, with a rolling speed of 0.343 m / s; the second pass has a height of 135.01 mm and a width of 180.01 mm, with a rolling speed of 0.512 m / s; the third pass has a height of 148.4 mm and a width of 148.4 mm, with a rolling speed of 0.613 m / s; the finished product is produced after the seventh pass.

[0030] 8) Insulation Steel insulation is applied, with the temperature in the insulation pit at 580℃ for 49 hours, and the temperature upon exiting the pit at 90℃.

[0031] 9) Heat treatment The heat-treated steel is then subjected to heat treatment, which includes the following steps: (1) Quenching: 850℃, hold for 1.1h, oil cooling; (2) Tempering: 560℃, hold for 2.2h, then water-cooled.

[0032] Example 2 1. Chemical composition of steel bars for sucker rods The chemical composition by mass percentage is: C: 0.42%, Si: 0.27%, Mn: 0.59%, P: 0.008%, S: 0.004%, Cr: 0.98%, Ni: 0.05%, Mo: 0.19%, V: 0.08%, Cu: 0.04%, with the balance being iron and unavoidable impurities.

[0033] 2. Manufacturing process of steel bars for sucker rods Process route: Eco-friendly electric furnace + LF refining + RH refining + continuous casting → annealing → heating furnace heating → rolling → holding → heat treatment. Among them: 1) Eco-friendly electric furnace smelting The smelting process, based on mass fraction, employs 100% scrap steel, comprising 76% heavy scrap and 24% light scrap. The electrode heating time is 18 minutes, the tapping temperature is 1545℃, and the initial carbon content (C) and phosphorus content (P) at tapping are 0.07% and 0.007%, respectively. Auxiliary materials and alloys are added when 1 / 4 of the steel has been tapped. The smelting cycle is 36 minutes, the oxygen content in the molten steel is 527 ppm, and the furnace oxygen consumption is 15 m³ / min. 3 / t steel. Alloy addition per ton of steel: silicon-manganese alloy 6.6kg / t, high-carbon ferrochrome 16.6kg / t, aluminum wire segments ( 12mm) 1.5kg / t. Auxiliary material addition per ton of steel: Steel ladle ash 5.8kg / t, active lime ( 30mm) 34kg / t, dolomite ( 35mm) 26kg / t, coke granules 14kg / t.

[0034] 2) LF furnace refining The LF inlet temperature is 1527℃, and a high current of 35400A is used for heating and slag formation. When the slag surface fluctuates and the molten steel and electric arc are not exposed, 11.3 kg / t of active lime is added. After 13 minutes, the first sample is taken for chemical composition analysis. According to the target chemical composition values, alloy, silicon carbide, and alumina balls are added, along with coke particles for carbonization. The alloy, silicon carbide, alumina balls, and coke particles should be added to the argon flow to promote rapid melting and homogenization. When the molten steel temperature reaches 1585℃, deoxidizer aluminum segments are added. 0.41 kg / t of slag (12mm) was added to adjust the slag basicity. The furnace door was closed for 16 minutes. When the molten steel temperature reached 1606℃, a second sample was taken to analyze the chemical composition to confirm the deviation of each chemical element content from the target value. After the second sample was taken, the furnace was left when the molten steel temperature reached 1618℃. The LF smelting cycle was 85 minutes, with a net clearance of 450 mm and a slag thickness of 140 mm. Additional alloys added per ton of steel: ferrosilicon 0.71 kg / t, high-carbon ferromanganese 1.73 kg / t, high-carbon ferrochrome 0.91 kg / t, ferromolybdenum 3.5 kg / t, ferrovanadium (FeV50-B) 3.6 kg / t. Additional auxiliary materials added per ton of steel: coke particles 0.88 kg / t, silicon carbide 2.0 kg / t, alumina balls 1.6 kg / t.

[0035] 3) RH refining The inlet temperature was 1627℃, and the operation time was 42 minutes. Before starting the vacuum pump, the argon pressure was controlled at 0.18 MPa to ensure the molten steel was not exposed due to slight movement of the slag surface. Timing began when the vacuum reached 97 Pa and was maintained for 18 minutes. Simultaneously, the argon pressure was adjusted to 0.4 MPa, and the repressurization temperature was 1585℃. After static argon blowing, 0.62 kg / t of carbonized rice husk was added as a covering agent. The clearance was 395 mm, and the outlet temperature was 1574℃. After breaking the vacuum, silicon-calcium alloy cored wire was added. 14mm) 0.82kg / t.

[0036] 4) Continuous casting The ladle temperature upon arrival is 1565℃, the tundish H is controlled at 1.4ppm, the casting time is 45min, the superheat is 22℃, the casting speed is 0.45m / min, the entire casting process is protected, and 2.0kg / t of medium carbon steel protective slag is used in the crystallizer.

[0037] 5) Annealing of the cast billet The billet is annealed in an annealing furnace at a heating rate of 1.5℃ / min, reaching 626℃, and held for 5.7 hours. It is then cooled in the furnace and removed from the furnace at 80℃.

[0038] 6) Heating The initial temperature in the heating furnace is 560℃; the preheating section temperature is required to be 790℃ for 1.4 hours; the second heating section temperature is required to be 904℃ for 2.0 hours; the first heating section temperature is required to be 1217℃ for 1.4 hours; the soaking section temperature is required to be 1205℃ for 1.3 hours; and the tapping temperature is 1196℃.

[0039] 7) Rolling Preliminary rolling: 11 passes, turning steel → Pass 1: Width 408.1mm, Height 420.1mm, Reduction 65mm, Roll Gap 260.1mm → Pass 2: Width 428.1mm, Height 355mm, Reduction 65mm, Roll Gap 195mm → Turning steel → Pass 3: Width 371mm, Height 348.1mm, Reduction 80.1mm, Roll Gap 188.1mm → Pass 4: Width 394mm, Height 273.1mm, Reduction 75mm, Roll Gap 113.1mm → Turning steel → Pass 5: Width 286.1mm, Height 349.1mm, Reduction 45.1mm, Roll Gap 189mm → Pass 6: Width 300.1mm, Height 304.0mm 1mm, reduction 45.1mm, roll gap 144mm → Turn over → 7th pass: width 315mm, height 254.1mm, reduction 50.1mm, roll gap 94mm → 8th pass: width 330.1mm, height 204.1mm, reduction 50mm, roll gap 44mm → Turn over → 9th pass: width 213.1mm, height 230mm, reduction 30mm, roll gap 140.1mm → 10th pass: width 252.1mm, height 270.1mm, reduction 30.1mm, roll gap 109mm → 11th pass: width 298mm, height 250.1mm, reduction 20.1mm, roll gap 88mm, then enters a 7-stand continuous rolling mill for rolling.

[0040] Continuous rolling process: 7 passes. Pass 1: Height 229.01mm, width 245.01mm, rolling speed 0.27m / s; Pass 2: Height 192.01mm, width 235.01mm, rolling speed 0.31m / s; Pass 3: Height 200.01mm, width 195mm, rolling speed 0.352m / s; Pass 4: Height 166.01mm, width... The first pass has a height of 206.01 mm and a width of 176 mm, with a rolling speed of 0.343 m / s. The second pass has a height of 135 mm and a width of 180.01 mm, with a rolling speed of 0.512 m / s. The third pass has a height of 148.4 mm and a width of 148.41 mm, with a rolling speed of 0.615 m / s. The finished product is produced after the seventh pass.

[0041] 8) Insulation Steel insulation, the temperature in the insulation pit is 590℃, the insulation time is 50 hours, and the temperature when it comes out of the pit is 85℃.

[0042] 9) Heat treatment The heat-treated steel is then subjected to heat treatment, which includes the following steps: (1) Quenching: 850℃, hold for 1.1h, oil cooling; (2) Tempering: 560℃, hold for 2.2h, then water-cooled.

[0043] Example 3 1. Chemical composition of steel bars for sucker rods The chemical composition by mass percentage is: C: 0.41%, Si: 0.26%, Mn: 0.58%, P: 0.009%, S: 0.005%, Cr: 1.01%, Ni: 0.05%, Mo: 0.19%, V: 0.08%, Cu: 0.05%, with the balance being iron and unavoidable impurities.

[0044] 2. Manufacturing process of steel bars for sucker rods Process route: Eco-friendly electric furnace + LF refining + RH refining + continuous casting → annealing → heating furnace heating → rolling → holding → heat treatment. Among them: 1) Eco-friendly electric furnace smelting The smelting process, based on mass fraction, employs 100% scrap steel, comprising 75% heavy scrap and 25% light scrap. The electrode heating time is 18 minutes, the tapping temperature is 1546℃, and the carbon content at tapping is 0.07% and phosphorus content is 0.008%. Auxiliary materials and alloys are added when 1 / 4 of the steel has been tapped. The smelting cycle is 34 minutes, the oxygen content in the molten steel is 527 ppm, and the furnace oxygen consumption is 15 m³ / min. 3 / t steel. Alloy addition per ton of steel: silicon-manganese alloy 6.6kg / t, high-carbon ferrochrome 16.6kg / t, aluminum wire segments ( 12mm) 1.6kg / t. Auxiliary material addition per ton of steel: Steel ladle ash 5.9kg / t, active lime ( 30mm) 34kg / t, dolomite ( 35mm) 26kg / t, coke granules 13kg / t.

[0045] 2) LF furnace refining The LF inlet temperature is 1525℃, and a high current of 35600A is used for heating and slag formation. When the slag surface fluctuates and the molten steel and electric arc are not exposed, 11.3 kg / t of active lime is added. After 12 minutes, the first sample is taken for chemical composition analysis. According to the target chemical composition values, alloy, silicon carbide, and alumina balls are added, along with coke particles for carbonization. The alloy, silicon carbide, alumina balls, and coke particles should be added to the argon flow to promote rapid melting and homogenization. When the molten steel temperature reaches 1585℃, deoxidizer aluminum segments are added. 0.41 kg / t of slag (12mm) was added to adjust the slag basicity. The furnace door was closed for 16 minutes. When the molten steel temperature reached 1605℃, a second sample was taken to analyze the chemical composition to confirm the deviation of each chemical element content from the target value. After the second sample was taken, the furnace was left when the molten steel temperature reached 1618℃. The LF smelting cycle was 86 minutes, with a net clearance of 450 mm and a slag thickness of 138 mm. Additional alloys added per ton of steel: ferrosilicon 0.71 kg / t, high-carbon ferromanganese 1.72 kg / t, high-carbon ferrochrome 0.91 kg / t, ferromolybdenum 3.6 kg / t, ferrovanadium (FeV50-B) 3.6 kg / t. Additional auxiliary materials added per ton of steel: coke particles 0.88 kg / t, silicon carbide 2.1 kg / t, alumina balls 1.6 kg / t.

[0046] 3) RH refining The inlet temperature was 1625℃, and the operation time was 43 minutes. Before starting the vacuum pump, the argon pressure was controlled at 0.16 MPa to ensure the molten steel was not exposed due to slight movement of the slag surface. Timing began when the vacuum reached 98 Pa and was maintained for 17 minutes. Simultaneously, the argon pressure was adjusted to 0.4 MPa, and the repressurization temperature was 1586℃. After static argon blowing, 0.62 kg / t of carbonized rice husk was added as a covering agent. The clearance was 395 mm, and the outlet temperature was 1575℃. After breaking the vacuum, silicon-calcium alloy cored wire was added. 14mm) 0.81kg / t.

[0047] 4) Continuous casting The ladle temperature upon arrival is 1564℃, the tundish H is controlled at 1.5ppm, the casting time is 43min, the superheat is 23℃, the casting speed is 0.45m / min, the entire casting process is protected, and 2.1kg / t of medium carbon steel protective slag is used in the crystallizer.

[0048] 5) Annealing of the cast billet The billet is annealed in an annealing furnace at a heating rate of 1.5℃ / min, reaching 625℃, and held for 5.8 hours. It is then cooled in the furnace and removed from the furnace at 80℃.

[0049] 6) Heating The initial temperature in the heating furnace is 560℃; the preheating section temperature is required to be 790℃ for 1.4 hours; the second heating section temperature is required to be 905℃ for 1.9 hours; the first heating section temperature is required to be 1215℃ for 1.4 hours; the soaking section temperature is required to be 1205℃ for 1.2 hours; and the tapping temperature is 1195℃.

[0050] 7) Rolling Preliminary rolling: 11 passes, turning over → Pass 1: Width 408.1mm, Height 420mm, Reduction 65.1mm, Roll Gap 260mm → Pass 2: Width 428.1mm, Height 355.1mm, Reduction 65mm, Roll Gap 195.1mm → Turning over → Pass 3: Width 371.1mm, Height 348.1mm, Reduction 80mm, Roll Gap 188.1mm → Pass 4: Width 394.1mm, Height 273.1mm, Reduction 75mm, Roll Gap 113.1mm → Turning over → Pass 5: Width 286.1mm, Height 349mm, Reduction 45mm, Roll Gap 189.1mm → Pass 6: Width 300.1mm, Height 304mm m, reduction 45.1mm, roll gap 144.1mm → turn steel → 7th pass 315mm wide, 254.1mm high, reduction 50.1mm, roll gap 94.1mm → 8th pass 330.1mm wide, 204mm high, reduction 50.1mm, roll gap 44.1mm → turn steel → 9th pass 213mm wide, 230.1mm high, reduction 30mm, roll gap 140.1mm → 10th pass 252.1mm wide, 270mm high, reduction 30.1mm, roll gap 109.1mm → 11th pass 298mm wide, 250mm high, reduction 20.1mm, roll gap 88mm, then enters a 7-stand continuous rolling mill for rolling.

[0051] Continuous rolling process: 7 passes. Pass 1: Height 229–229.01 mm, width 245–245.01 mm, rolling speed 0.27 m / s; Pass 2: Height 192.01 mm, width 235.01 mm, rolling speed 0.312 m / s; Pass 3: Height 200 mm, width 195.01 mm, rolling speed 0.352 m / s; Pass 4: Height 166.01 mm The first pass has a height of 174.01 mm, a width of 176.01 mm, and a rolling speed of 0.341 m / s; the second pass has a height of 135.01 mm, a width of 180 mm, and a rolling speed of 0.512 m / s; the third pass has a height of 148.41 mm, a width of 148.41 mm, and a rolling speed of 0.613 m / s; the finished product is produced after the seventh pass.

[0052] 8) Insulation Steel insulation: the temperature in the insulation pit is 580℃, the insulation time is 49 hours, and the temperature when it comes out of the pit is 80℃.

[0053] 9) Heat treatment The heat-treated steel is then subjected to heat treatment, which includes the following steps: (1) Quenching: 850℃, hold for 1.1h, oil cooling; (2) Tempering: 560℃, hold for 2.2h, then water-cooled.

[0054] Example 4 1. Chemical composition of steel bars for sucker rods The chemical composition by mass percentage is: C: 0.41%, Si: 0.27%, Mn: 0.60%, P: 0.008%, S: 0.004%, Cr: 1.00%, Ni: 0.06%, Mo: 0.18%, V: 0.09%, Cu: 0.05%, with the balance being iron and unavoidable impurities.

[0055] 2. Manufacturing process of steel bars for sucker rods Process route: Eco-friendly electric furnace + LF refining + RH refining + continuous casting → annealing → heating furnace heating → rolling → holding → heat treatment. Among them: 1) Eco-friendly electric furnace smelting The smelting process, based on mass fraction, employs 100% scrap steel, comprising 76% heavy scrap and 24% light scrap. The electrode heating time is 18 minutes, the tapping temperature is 1547℃, and the initial carbon content (C) and phosphorus content (P) at tapping are 0.07%. Auxiliary materials and alloys are added when 1 / 4 of the steel has been tapped. The smelting cycle is 35 minutes, the oxygen content in the molten steel is 525 ppm, and the furnace oxygen consumption is 15 m³ / min. 3 / t steel. Alloy addition per ton of steel: silicon-manganese alloy 6.6kg / t, high-carbon ferrochrome 16.6kg / t, aluminum wire segments ( 12mm) 1.5kg / t. Auxiliary material addition per ton of steel: Steel ladle ash 5.8kg / t, active lime ( 30mm) 33kg / t, dolomite ( 35mm) 26kg / t, coke granules 14kg / t.

[0056] 2) LF furnace refining The LF inlet temperature is 1524℃, and a high current of 35500A is used for heating and slag formation. When the slag surface fluctuates and the molten steel and electric arc are not exposed, 11.2 kg / t of active lime is added. After 12 minutes, the first sample is taken for chemical composition analysis. According to the target chemical composition values, alloy, silicon carbide, and alumina balls are added, along with coke particles for carbonization. The alloy, silicon carbide, alumina balls, and coke particles should be added to the argon flow to promote rapid melting and homogenization. When the molten steel temperature reaches 1585℃, deoxidizer aluminum segments are added. 0.40 kg / t of slag (12mm) was added to adjust the slag basicity. The furnace door was closed for 16 minutes. When the molten steel temperature reached 1606℃, a second sample was taken to analyze the chemical composition to confirm the deviation of each chemical element content from the target value. After the second sample was taken, the furnace was left when the molten steel temperature reached 1617℃. The LF smelting cycle was 85 minutes, with a net clearance of 450 mm and a slag thickness of 140 mm. The following alloys were added per ton of steel: ferrosilicon 0.71 kg / t, high-carbon ferromanganese 1.73 kg / t, high-carbon ferrochrome 0.91 kg / t, ferromolybdenum 3.5 kg / t, and ferrovanadium (FeV50-B) 3.6 kg / t. The following auxiliary materials were added per ton of steel: coke particles 0.87 kg / t, silicon carbide 2.1 kg / t, and alumina balls 1.6 kg / t.

[0057] 3) RH refining The inlet temperature was 1625℃, and the operation time was 42 minutes. Before starting the vacuum pump, the argon pressure was controlled at 0.2 MPa to ensure the molten steel was not exposed due to slight movement of the slag surface. Timing began when the vacuum reached 97 Pa and was maintained for 17 minutes. Simultaneously, the argon pressure was adjusted to 0.4 MPa, and the re-pressure temperature was 1584℃. After static argon blowing, 0.63 kg / t of carbonized rice husk was added as a covering agent. The clearance was 395 mm, and the outlet temperature was 1576℃. After breaking the vacuum, silicon-calcium alloy cored wire was added. 14mm) 0.83kg / t.

[0058] 4) Continuous casting The ladle temperature upon arrival was 1562℃, the H concentration in the tundish was controlled at 1.3ppm, the casting time was 43min, the superheat was 22℃, the casting speed was 0.44m / min, and the entire casting process was protected. 2.1kg / t of medium carbon steel protective slag was used in the crystallizer.

[0059] 5) Annealing of the cast billet The billet is annealed in an annealing furnace at a heating rate of 1.5℃ / min, reaching 624℃, and held for 5.8 hours. It is then cooled in the furnace and removed from the furnace at 80℃.

[0060] 6) Heating Heating process: Inlet temperature of 560℃, preheating zone temperature requirement of 790℃, time 1.4h; heating zone 2 temperature requirement of 905℃, time 2.0h; heating zone 1 temperature requirement of 1214℃, time 1.4h; soaking zone temperature requirement of 1205℃, time 1.3h; tapping temperature of 1197℃.

[0061] 7) Rolling Preliminary rolling: 11 passes, turning over → Pass 1: Width 408.1mm, Height 420mm, Reduction 65.1mm, Roll gap 260mm → Pass 2: Width 428.1mm, Height 355mm, Reduction 65.1mm, Roll gap 195mm → Turning over → Pass 3: Width 371mm, Height 348.1mm, Reduction 80mm, Roll gap 188.1mm → Pass 4: Width 394mm, Height 273.1mm, Reduction 75mm, Roll gap 113.1mm → Turning over → Pass 5: Width 286mm, Height 349mm, Reduction 45.1mm, Roll gap 189mm → Pass 6: Width 300.1mm, Height 420mm, Reduction 65.1mm, Roll gap 260mm → Pass 6: Width 300.1mm, Height 420mm, Reduction 65.1mm, Roll gap 195mm → Turning over → Pass 3: Width 371mm, Height 348.1mm, Reduction 80mm, Roll gap 188.1mm → Pass 4: Width 394mm, Height 273.1mm, Reduction 75mm, Roll gap 113.1mm → Turning over → Pass 5: Width 286mm, Height 349mm, Reduction 45.1mm, Roll gap 189mm → Pass 6: Width 300.1mm, Height 420mm, Reduction 65.1mm, Roll gap 195mm → Turning over → Pass 6: Width 300.1mm, Height 420mm, Reduction 65.1mm, Roll gap 195mm → Turn 304mm, reduction 45mm, roll gap 144.1mm → Turn over → 7th pass: width 315mm, height 254.1mm, reduction 50mm, roll gap 94mm → 8th pass: width 330mm, height 204mm, reduction 50.1mm, roll gap 44mm → Turn over → 9th pass: width 213.1mm, height 230mm, reduction 30mm, roll gap 140mm → 10th pass: width 252mm, height 270mm, reduction 30.1mm, roll gap 109mm → 11th pass: width 298mm, height 250.1mm, reduction 20mm, roll gap 88mm, then enters a 7-stand continuous rolling mill for rolling.

[0062] Continuous rolling process: 7 passes. Pass 1: Height 229mm, width 245.01mm, rolling speed 0.272m / s; Pass 2: Height 192.01mm, width 235mm, rolling speed 0.312m / s; Pass 3: Height 200.01mm, width 195mm, rolling speed 0.352m / s; Pass 4: Height 166.01mm, width 206mm. The first pass has a height of 174 mm and a width of 176.01 mm, with a rolling speed of 0.437 m / s; the second pass has a height of 135.01 mm and a width of 180.01 mm, with a rolling speed of 0.510 m / s; the third pass has a height of 148.41 mm and a width of 148.41 mm, with a rolling speed of 0.615 m / s; the finished product is produced after the seventh pass.

[0063] 8) Insulation Steel insulation: the temperature in the insulation pit is 580℃, the insulation time is 51 hours, and the temperature when it comes out of the pit is 70℃.

[0064] 9) Heat treatment The heat-treated steel is then subjected to heat treatment, which includes the following steps: (1) Quenching: 850℃, hold for 1.1h, oil cooling; (2) Tempering: 560℃, hold for 2.2h, then water-cooled.

[0065] Example 5 1. Chemical composition of steel bars for sucker rods The chemical composition by mass percentage is: C: 0.40%, Si: 0.25%, Mn: 0.59%, P: 0.010%, S: 0.005%, Cr: 1.02%, Ni: 0.05%, Mo: 0.19%, V: 0.08%, Cu: 0.05%, with the balance being iron and unavoidable impurities.

[0066] 2. Manufacturing process of steel bars for sucker rods Process route: Eco-friendly electric furnace + LF refining + RH refining + continuous casting billet → annealing → heating furnace heating → rolling → holding → heat treatment. Among them: 1) Eco-friendly electric furnace smelting The smelting process, based on mass fraction, employs 100% scrap steel, comprising 75% heavy scrap and 24% light scrap. The electrode heating time is 18 minutes, the tapping temperature is 1546℃, and the initial carbon content (C) and phosphorus content (P) at tapping are 0.07% and 0.009%, respectively. Auxiliary materials and alloys are added when 1 / 4 of the steel has been tapped. The smelting cycle is 36 minutes, the oxygen content in the molten steel is 525 ppm, and the furnace oxygen consumption is 15 m³ / min. 3 / t steel. Alloy addition per ton of steel: silicon-manganese alloy 6.6kg / t, high-carbon ferrochrome 16.6kg / t, aluminum wire segments ( 12mm) 1.6kg / t. Auxiliary material addition per ton of steel: Steel ladle ash 5.9kg / t, active lime ( 30mm) 34kg / t, dolomite ( 35mm) 26kg / t, coke granules 13kg / t.

[0067] 2) LF furnace refining The LF inlet temperature is 1525℃, and the slag is heated by a high current of 35600A. When the slag surface fluctuates and the molten steel and electric arc are not exposed, 11.3 kg / t of active lime is added. After 13 minutes, the first sample is taken for chemical composition analysis. Alloy, silicon carbide, and alumina balls are added according to the target chemical composition values, and coke particles are added to increase carbon content. Alloy, silicon carbide, alumina balls, and coke particles should be added to the argon flow to promote rapid melting and homogenization of the alloy, silicon carbide, alumina balls, and coke particles. When the molten steel temperature reaches 1585℃, deoxidizer aluminum segments are added. 0.41 kg / t of slag (12mm) was added to adjust the slag basicity. The furnace door was closed for 16 minutes. When the molten steel temperature reached 1607℃, a second sample was taken to analyze the chemical composition to confirm the deviation of each chemical element content from the target value. After the second sample was taken, the furnace was left when the molten steel temperature reached 1618℃. The LF smelting cycle was 87 minutes, with a net clearance of 450 mm and a slag thickness of 140 mm. Additional alloys added per ton of steel: ferrosilicon 0.71 kg / t, high-carbon ferromanganese 1.72 kg / t, high-carbon ferrochrome 0.91 kg / t, ferromolybdenum 3.6 kg / t, ferrovanadium (FeV50-B) 3.6 kg / t. Additional auxiliary materials added per ton of steel: coke particles 0.87 kg / t, silicon carbide 2.0 kg / t, alumina balls 1.6 kg / t.

[0068] 3) RH refining The inlet temperature was 1625℃, and the operation time was 43 minutes. Before starting the vacuum pump, the argon pressure was controlled at 0.2 MPa to ensure the molten steel was not exposed due to slight movement of the slag surface. Timing began when the vacuum reached 97 Pa and was maintained for 16 minutes. Simultaneously, the argon pressure was adjusted to 0.4 MPa, and the re-pressure temperature was 1585℃. After static argon blowing, 0.62 kg / t of carbonized rice husk was added as a covering agent. The clearance was 396 mm, and the outlet temperature was 1575℃. After breaking the vacuum, silicon-calcium alloy cored wire was added. 14mm) 0.82kg / t.

[0069] 4) Continuous casting The ladle temperature upon arrival is 1566℃, the tundish H is controlled at 1.4ppm, the casting time is 45min, the superheat is 22℃, the casting speed is 0.45m / min, the entire casting process is protected, and 2.0kg / t of medium carbon steel protective slag is used in the crystallizer.

[0070] 5) Annealing of the cast billet The billet is annealed in an annealing furnace at a heating rate of 1.5℃ / min, reaching 625℃, and held for 5.8 hours. It is then cooled in the furnace and removed from the furnace at 80℃.

[0071] 6) Heating The initial temperature in the heating furnace is 560℃; the preheating section temperature is required to be 790℃ for 1.3 hours; the second heating section temperature is required to be 905℃ for 1.95 hours; the first heating section temperature is required to be 1215℃ for 1.4 hours; the soaking section temperature is required to be 1205℃ for 1.2 hours; and the tapping temperature is 1195℃.

[0072] 7) Rolling Preliminary rolling: 11 passes, turning steel → Pass 1: Width 408mm, Height 420.1mm, Reduction 65mm, Roll Gap 260mm → Pass 2: Width 428.1mm, Height 355mm, Reduction 65.1mm, Roll Gap 195mm → Turning steel → Pass 3: Width 371mm, Height 348.1mm, Reduction 80mm, Roll Gap 188.1mm → Pass 4: Width 394mm, Height 273.1mm, Reduction 75mm, Roll Gap 113.1mm → Turning steel → Pass 5: Width 286.1mm, Height 349mm, Reduction 45.1mm, Roll Gap 189mm → Pass 6: Width 300.1mm, Height 304mm The steel is rolled with a reduction of 45.1 mm and a roll gap of 144 mm. It is then turned over and rolled in the 7th pass with a width of 315 mm, a height of 254.1 mm, a reduction of 50 mm, and a roll gap of 94.1 mm. The steel is then rolled in the 8th pass with a width of 330 mm, a height of 204.1 mm, a reduction of 50 mm, and a roll gap of 44.1 mm. It is then turned over and rolled in the 9th pass with a width of 213.1 mm, a height of 230 mm, a reduction of 30.1 mm, and a roll gap of 140.1 mm. The steel is then rolled in the 10th pass with a width of 252.1 mm, a height of 270.1 mm, a reduction of 30 mm, and a roll gap of 109.1 mm. The steel is then rolled in the 11th pass with a width of 298 mm, a height of 250.1 mm, a reduction of 20 mm, and a roll gap of 88 mm. Finally, the steel is rolled in a 7-stand continuous rolling mill.

[0073] Continuous rolling process: 7 passes. Pass 1: Height 229mm, width 245.01mm, rolling speed 0.272m / s; Pass 2: Height 192mm, width 235.01mm, rolling speed 0.312m / s; Pass 3: Height 200.01mm, width 195mm, rolling speed 0.352m / s; Pass 4: Height 166mm, width 206.01mm, rolling speed 0.343m / s; Pass 5: Height 174mm, width 176.01mm, rolling speed 0.437m / s; Pass 6: Height 135mm, width 180.01mm, rolling speed 0.512m / s; Pass 7: Height 148.41mm, width 148.41mm, rolling speed 0.615m / s; Finished product after 7 passes.

[0074] 8) Insulation Steel insulation: the temperature in the insulation pit is 575℃, the insulation time is 51 hours, and the temperature when it comes out of the pit is 80℃.

[0075] 9) Heat treatment The heat-treated steel is then subjected to heat treatment, which includes the following steps: (1) Quenching: 850℃, hold for 1.1h, oil cooling; (2) Tempering: 560℃, hold for 2.2h, then water-cooled.

[0076] Inspection results of finished products in Examples 1-5 (1) Low magnification structure of Φ146mm steel (finished steel obtained after heat preservation)

[0077] (2) Non-metallic inclusions in Φ146mm steel (finished steel obtained after heat preservation)

[0078] (3) Mechanical properties of Φ146mm steel (finished steel after heat treatment)

[0079] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A method for smelting steel bars for sucker rods using an eco-friendly electric furnace, characterized in that, The chemical composition of the steel rod used for the sucker rod, by mass percentage, is: C: 0.39%–0.43%, Si: 0.20%–0.35%, Mn: 0.52%–0.67%, P: ≤0.012%, S: ≤0.006%, Cr: 0.92%–1.07%, Ni: ≤0.20%, Mo: 0.16%–0.23%, V: 0.06%–0.10%, Cu: ≤0.10%, with the balance being iron and unavoidable impurities; The method includes: ecological electric furnace → LF refining → RH refining → continuous casting → annealing → heating furnace heating → rolling → heat preservation; The eco-friendly electric furnace smelting process is as follows: scrap steel is used for electrode heating for 16-20 minutes; tapping temperature is 1540-1550℃; carbon content at tapping is 0.06-0.08%, phosphorus ≤ 0.010%; auxiliary materials and alloys are added when 1 / 4 to 1 / 3 of the steel has been tapped; the smelting cycle is 30-40 minutes; oxygen content in the molten steel is 520-530 ppm; and furnace oxygen consumption is 14-16 m³ / min. 3 / t steel; wherein, the scrap steel includes heavy scrap steel and light scrap steel, and by mass fraction, heavy scrap steel is 70% to 80% and light scrap steel is 20% to 30%; alloy addition per ton of steel: silicon manganese alloy 6.5 to 6.7 kg / t, high carbon ferrochrome 16.5 to 16.7 kg / t, aluminum wire segments 1.5 to 1.6 kg / t; auxiliary material addition per ton of steel: steel ladle ash 5.8 to 5.9 kg / t, quicklime 33 to 34 kg / t, dolomite 25 to 26 kg / t, coke granules 13 to 14 kg / t; The LF refining process is as follows: The LF inlet temperature is 1520–1530℃, and the slag is heated by a high current of 35000–36000A. When the slag surface fluctuates and the molten steel and electric arc are not exposed, 11–11.5 kg / t of active lime is added. After 10–15 minutes, the first sample is taken for chemical composition analysis. Alloys, silicon carbide, and alumina balls are added according to the target values ​​in the chemical composition, and coke particles are added to increase carbon content. When the molten steel temperature reaches 1580–1590℃, 0.4–0.42 kg / t of deoxidizer is added to adjust the slag basicity. The furnace door is closed for 15–17 minutes. When the molten steel temperature reaches 1600–1610℃, a second sample is taken for chemical composition analysis to confirm the composition of each chemical element. The deviation of the content from the target value is considered. After the second sample is taken, the steel is removed from the station when the temperature reaches 1615-1620℃. The LF smelting cycle is 80-90 minutes, the net clearance is 440-460 mm, and the slag thickness is 130-150 mm. Among them, the amount of alloys added per ton of steel is: ferrosilicon 0.70-0.72 kg / t, high-carbon ferromanganese 1.70-1.75 kg / t, high-carbon ferrochrome 0.90-0.92 kg / t, ferromolybdenum 3.5-3.6 kg / t, and ferrovanadium 3.5-3.6 kg / t. The amount of auxiliary materials added per ton of steel is: coke particles 0.85-0.90 kg / t, silicon carbide 2.0-2.1 kg / t, and alumina balls 1.5-1.6 kg / t. The RH refining process is as follows: Inlet temperature 1620–1630℃, operating time 40–45 minutes; argon pressure controlled at 0.1–0.3 MPa before vacuum pump startup, ensuring the molten steel is not exposed by slight slag movement; timing begins when vacuum reaches 95–100 Pa, held for 15–20 minutes, while simultaneously adjusting argon pressure to 0.3–0.5 MPa; repressurization temperature 1580–1590℃; after static argon blowing, a covering agent is added, maintaining a clearance of 390–400 mm; outlet temperature 1570–1580℃; after vacuum breaking, 0.80–0.85 kg / t of silicon-calcium alloy cored wire is added. The continuous casting process is as follows: ladle arrival temperature 1560~1570℃, tundish H control ≤1.8ppm, casting time 40min~50min, superheat 20~25℃, casting speed 0.44~0.45m / min; The annealing process is as follows: the billet is annealed in an annealing furnace at a heating rate of 1.4 to 1.5°C / min, reaching 620 to 630°C, and held at that temperature for 5.6 to 6.0 hours. Then, it is cooled in the furnace and removed from the furnace when the temperature is ≤90°C. The heating process is as follows: furnace inlet temperature 550℃~570℃, preheating section temperature 780℃~800℃, time 1.3~1.4h; heating section 2 temperature 900℃~910℃, time 1.9~2.0h; heating section 1 temperature 1210℃~1220℃, time 1.3~1.5h; soaking section temperature 1200℃~1210℃, time 1.2~1.3h; tapping temperature 1190℃~1200℃. The insulation process is as follows: steel insulation, temperature in the lower insulation pit ≥550℃, insulation for 48~52h, and temperature upon exiting the pit ≤100℃; The heat-treated steel is then subjected to heat treatment, which includes the following steps: (1) Quenching: 840~860℃, hold for 1.0~1.2h, oil cooling; (2) Tempering: 550~570℃, heat preservation for 2.1~2.3h, water cooling.

2. The method for smelting steel bars for sucker rods using an eco-friendly electric furnace according to claim 1, characterized in that, In the LF refining process, alloys, silicon carbide, alumina balls, and coke particles are added to the argon gas stream; the deoxidizer is aluminum wire segments.

3. The method for smelting steel bars for sucker rods using an eco-friendly electric furnace according to claim 1, characterized in that, In the RH refining process, the covering agent is carbonized rice husk, and the amount of covering agent added is 0.6-0.65 kg / t steel.

4. The method for smelting steel bars for sucker rods using an eco-friendly electric furnace according to claim 1, characterized in that, During the continuous casting process, the casting is protected throughout the entire process, and the mold flux uses 2.0 to 2.1 kg / t of medium carbon steel flux.

5. The method for smelting steel bars for sucker rods using an eco-friendly electric furnace according to claim 2, characterized in that, The diameter of the aluminum wire segment is 10-16 mm, the diameter of the active lime is 10-70 mm, the diameter of the dolomite is 10-60 mm, the ferrovanadium is FeV50-B, and the diameter of the silicon-calcium alloy cored wire is 14-15 mm.

6. The method for smelting steel bars for sucker rods using an eco-friendly electric furnace according to claim 1, characterized in that, The rolling process is as follows: (1) Initial rolling: 11 passes, turning the steel → Pass 1: width 408-408.1mm, height 420-420.1mm, reduction 65-65.1mm, roll gap 260-260.1mm → Pass 2: width 428-428.1mm, height 355-355.1mm, reduction 65-65.1mm, roll gap 195-195.1mm → Turning the steel → Pass 3: width 371-371.1mm, height 348-348.1mm, reduction 80-80.1mm width, 188-188.1mm roll gap → 4th pass: 394-394.1mm width, 273-273.1mm height, 75-75.1mm reduction, 113-113.1mm roll gap → Turning steel → 5th pass: 286-286.1mm width, 349-349.1mm height, 45-45.1mm reduction, 189-189.1mm roll gap → 6th pass: 300-300.1mm width, 304-305mm height 4.01mm, reduction 45-45.1mm, roll gap 144-144.1mm → Turning steel → 7th pass: width 315-315.1mm, height 254-254.1mm, reduction 50-50.1mm, roll gap 94-94.1mm → 8th pass: width 330-330.1mm, height 204-204.1mm, reduction 50-50.1mm, roll gap 44-44.1mm → Turning steel → 9th pass: width 213-213.1mm The first pass has a width of 230–230.1 mm, a reduction of 30–30.1 mm, and a roll gap of 140–140.1 mm. The 10th pass has a width of 252–252.1 mm, a height of 270–270.1 mm, a reduction of 30–30.1 mm, and a roll gap of 109–109.1 mm. The 11th pass has a width of 298–298.1 mm, a height of 250–250.1 mm, a reduction of 20–20.1 mm, and a roll gap of 88–88.1 mm. Then it enters the continuous rolling mill for rolling. (2) Continuous rolling of finished product: 7 passes. Pass 1: Height 229–229.01 mm, width 245–245.01 mm, rolling speed 0.27–0.272 m / s; Pass 2: Height 192–192.01 mm, width 235–235.01 mm, rolling speed 0.31–0.312 m / s; Pass 3: Height 200–200.01 mm, width 195–195.01 mm, rolling speed 0.35–0.352 m / s; Pass 4: Height 166–166.01 mm, width 206–200.01 mm. The first pass has a diameter of 6.01 mm and a rolling speed of 0.341–0.343 m / s; the fifth pass has a height of 174–174.01 mm and a width of 176–176.01 mm, with a rolling speed of 0.435–0.437 m / s; the sixth pass has a height of 135–135.01 mm and a width of 180–180.01 mm, with a rolling speed of 0.510–0.512 m / s; the seventh pass has a height of 148.4–148.41 mm and a width of 148.4–148.41 mm, with a rolling speed of 0.613–0.615 m / s; the finished product is produced after the seventh pass.

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